What Is Kallakkadal (Sea Swell) Which Kerala, Tamil Nadu Coastal Areas Are Warned About

Kallakkadal, a name that people in Kerala’s coastal areas recall with fear has once again threatened them as the Indian National Centre for Ocean Information Services (INCOIS) today warned the coaster regions of the potential Kallakkadal phenomenon.

The alert has directed people against getting into the sea, and engaging in beach activities and cautioned the fishermen. Notably coastal areas in Alappuzha, Kollam, and Thiruvananthapuram districts were hit with the phenomenon in March this year. Following the miseries, the authorities had opened a relief camp for the coastal people.

What is the Kallakkadal Phenomenon

A coastal flooding that mainly occurs before the beginning of the monsoon season, Kallakkadal is a series of high sea waves or swell waves. The phenomenon is mostly seen on India’s southern coast.  Kallakkadal is formed through a combination of wind strength and wind duration generated some distance away in the ocean. In such a situation, the process of energy transfer from air into water causes huge waves, which spread across the sea, and reach the shore.

Notably, while ordinary sea chop is generated by local winds, the size of the swell is coming from far away. Swimmers in the sea most often encounter swell, but the arrival of such swells into the coastal areas makes the region vulnerable.

The phenomenon mostly affects the southern states of Kerala and Tamil Nadu during the pre-monsoon season – from April to May.

Used by the local fisherman, the term “kallakkadal” is a Malayalam word meaning the sea thief, referring to the arrival of a sea thief. 

Kallakkadal is different from Tsunami because the waves created by Kallakkadal is comparatively small. Many people mistake Kallakkadal  as Tsunami, which is created due to some underwater disturbance like an earthquake.

However, though relatively small, the Kallakkadal should not be played down as it often causes widespread devastations to the coastal areas. 

Following the recurrent events, the Indian National Centre for Ocean Information Services (INCOIS) in 2020 launched a Swell Surge Forecast System which collects information on the phenomenon and issues warnings to the coastal region.